Process of assaying for silver.



JOSEPH HAIVIES, OF GOLDFIELD, NEVADA.

PROCESS OF ASSAYING FOB SILVER.

No Drawing.

Specification of Letters Patent.

Patented Nov. 9, 1969.

Application filed April 21, 1909. Serial No. 491,314.

To all whom it may concern:

Be it known that I, JosErH C. HAMES, a citizen of the United States, residing at Goldfield, in the county of Esmeralda and State of Nevada, have invented new and useful Improvements in Processes of Assaying for Silver, of which the following is a specification.

My present invention pertains to assaying, and consists in an expeditious and otherwise advantageous process of assaying.

In assaying for gold I take a definite quantity, say one-half assay ton, of pulp, and add to the same 17 parts of a composition consisting of the following ingredients, combined in substantially the proportions stated, viz:

Gum camphor 1 part.

Iodin crystals 20. 736 parts. Potassium iodid 41. 471 parts. Water 310 parts.

I find from experiments that the best results are obtained by adding to the pulp 3 parts of the camphor, iodin and potassium iodid in a dry state, and 14 parts of Water, in the order named, and then suitably stirring or agitating the mass.

To the solution from the assay described in the foregoing I add a dram of sodium amalgam, this latter to precipitate gold, after which the metallic gold may be recovered in any of the well known ways extant.

The generic assaying process and the specific process of assaying for gold, hereinbefore described, constitute the subject matter of my Letters-Patent No. 913,129.

In assaying for silver I practice the process described up to and including the addition of the gum camphor, iodin crystals and potassium iodid and the water to the pulp. I then add to the whole sodium cyanid corresponding in quantity to the pulp. Then I take the solution from said assay, and precipitate the silver on zinc shavings or with zinc dust. With this done, the mass of zinc shavings or zinc dust is dissolved in nitric acid.

As an indicator solution I use one part of a suitable starch (preferably arrow-root starch) to one-hundred parts of water. The starch and water are mixed cold, and the solution is let come to a boil and is boiled approximately two minutes, and when cool is ready for use.

Experience has demonstrated that it is best to add one part of the starch solution to about ten parts of the silver nitrate solution.

In using a certain amount of ore pulp, say one-fourth (9 assay ton, for each ounce of silver represented in a ton of ore it Will require one drop or about one-twentieth of a cubic centimeter of standard iodin solution to cause the silver nitrate solution to take on a blue color. Different waters have different eifects on results, and therefore, in order to obtain exact results as to amount of iodin solution, I dissolve a weighed amount of C. P. silver in acid and titrate with the iodin solution, noting the amount of solution required to bring about the blue color. I have also found from ex perience that when starch is added to the silver nitrate solution, a small amount of sodium hyposulfite added to the solution will cause the same to quickly clarify. I would have it understood, however, that not enough sodium hyposulfite is used to cause the solution to become alkaline.

Having described my invention, what I claim and desire to secure by Letters-Patent, is:

1. The process of assaying for silver, which consists in adding to a quantity of ore pulp, camphor, iodin, potassium iodid and a solvent, adding sodium cyanid, precipitating the silver in the solution from the assay on zinc, dissolvin the precipitated silver in nitric acid, adding starchy matter to the solution, and determining the amount of silver in the solution.

2. The process of assaying for silver, which consists in adding to a quantity of ore pulp, camphor, iodin, potassium iodid and a solvent, adding sodium cyanid, precipitating the silver in the solution from the assay on zinc, dissolving the precipitated silver in nitric acid, adding starchy matter and sodium hyposulfite to the solution, and determining the amount of silver in the solution.

3. The process of assaying for silver, which consists in adding to a quantity of ore pulp, caniphor, iodin, potassium iodid and a solvent, adding sodium cyanid, precipitating the silver in the solution from the assay on zinc, dissolving the precipitated silver in nitric acid, adding indicator means to the said solution, and determining the amount of silverin the solution.

4:. The process of assaying for silver, which consists in adding to a quantity of ore pulp, caniphor, iodin, potassium iodid, and a solvent, adding sodium cyanid, precipitating the silver in the solution, dissolving the silver and ascertaining the quantity of silver in the solution.

The process of assaying for silver,

which consists in adding to a quantity of ore pulp, cainphor, iodin, potassium iodid, and a solvent, adding sodiuni cyanid, precipitating the silver in the solution, dissolving the precipitated silver, adding starchy matter to 20 JOSEPH G. HAMES.

lVitnesses C. O. FoL'rZ,

LILLIE B. ANDREWS. 

